In this article for the American Bar Association Antitrust Law Section's Compliance and Ethics Committee newsletter, Lauren Briggerman and co-author Sarah Flanagan (Associate General Counsel, Global Director of Antitrust Compliance, and Head of Americas Ethics and Legal Compliance at Intel) provide an overview of the new Department of Justice (DOJ)-wide Mergers & Acquisitions (M&A) Safe Harbor policy encouraging voluntary self-disclosure of misconduct discovered during due diligence, announced in an October 4 speech by Deputy Attorney General (DAG) Lisa O. Monaco. That policy rewards acquiring companies with a presumption of declined prosecution if they voluntarily report and remediate criminal conduct uncovered during the due diligence process within the safe harbor period, cooperate with DOJ's investigation, and agree to disgorgement and restitution. While the new policy gives acquiring companies increased certainty about when they may qualify for a DOJ declination, the deadlines leave little room for error or delay in detection, remediation, or decision-making regarding disclosures. The authors argue that even if acquiring companies have robust compliance programs and meet the reporting and remediation deadlines, they must consider whether the benefit of a conditional declination outweighs the potential burden on the company and its employees of a voluntary disclosure. Briggerman and Flanagan conclude that regardless of whether companies avail themselves of the Safe Harbor policy, an effective compliance program is the single greatest tool that companies have for efficiently and fulsomely detecting potential misconduct by an acquired company (and more generally) and remediating it to reduce risk to the business and shareholders going forward.